id summary reporter owner description type status priority component version resolution keywords cc guest host
8498 Taking a snapshot can revert recent disk writes in the running VM eric97 "Taking a snapshot with the VM running can revert recent disk writes in the VM. The snapshot itself '''does''' contain the changes, but the still-running VM does '''not'''. (Rather than trying to explain in this detail in running text, let me refer you to the ''The problem'' section below.)
The guest is System Rescue CD 2.0.1 (can be downloaded from http://www.sysresccd.org/). For this test, it suffices to boot from the CD image; one does ''not'' need to install a guest O/S in the VM.
=== To reproduce ===
==== Setup ====
This first part is setup, which should all go as expected:
1. Create a VM:
a. System is Linux/Ubuntu
a. Accept all further defaults
1. Attach systemrescuecd-x86-2.0.1.iso to the virtual CD-ROM
1. Boot, accepting all defaults
1. Use {{{cfdisk}}} to create a single 5-MB primary partition, /dev/sda1
1. Reboot (probably no longer necessary these days, but for the sake of
eliminating extraneous variables, it can't hurt)
1. Take a snapshot, using {{{Machine > Take Snapshot...}}} menu item
==== The problem ====
Here's where things get interesting. I'm attaching a screen capture,
annotated to show the point where I take the snapshot.
7. {{{od -c /dev/sda1}}} to verify that it contains all '\0' bytes
1. {{{echo hello >/dev/sda1}}} (It's not often do you do *that* on purpose :-) )
1. {{{od -c /dev/sda1}}} again to verify that the ""hello"" was written
1. Take a second snapshot, again using {{{Machine > Take Snapshot...}}}
1. {{{od -c /dev/sda1}}} yet again. It should still say ""hello\n" defect closed major other VirtualBox 4.0.4 fixed other other